1/6 the number of (n+2)X3 0..2 arrays with each 3X3 subblock containing two of one value, three of another, and four of the last.

A184404

1/6 the number of (n+2)X3 0..2 arrays with each 3X3 subblock containing two of one value, three of another, and four of the last.

Terms

    a(0) =1260a(1) =16140a(2) =201543a(3) =2563542a(4) =32546547a(5) =414199395a(6) =5273355420a(7) =67176457326a(8) =855995407713

External references